We shall continue our efforts to reconstitute and analyze important membrane transport systems, in particular the electrically gated Na and K channels, the acetylcholine receptor system and the mitochondrial electrontransport system. New methods are developed for the insertion of the isolated transport proteins into planar and large solvent free vesicular bilayers. The reconstituted membranes are studied by electrical, chemical and optical techniques in order to elucidate the molecular mechanisms controlling the transfer of ions and electrons across the membrane. Our recent work on electrically excitable bilayer membranes suggests that the gating process involves the insertion of channel precursors into the membrane hydrocarbon region and their subsequent aggregation into open channels. The detailed agreement of the current-voltage kinetics in excitable bilayers and nerve will be further investigated in an attempt to determine if the gating in nerve and receptors also proceeds by this mechanism. Molecular details of the gating process in excitable bilayers are investigated by optical methods using fluorescent voltage dependent channel formers.